Black May (36 page)

How much Horton was now beginning to edge from a defensive to an offensive posture, as a result of this battle and subsequent events in May and early June, is exemplified by his relatively open response to a recommendation put forward on 9 May by Captain McCoy, SO, EG3, in
Offa,
who thought that evasive tactics, such as those employed in the long routing of ONS.5 to the north, were wasteful and unnecessary. Echoing Gretton’s confidence in the close screen, McCoy argued that, “Escorts that are fitted with radar and which are handled with determination, will always defeat the U-boat at night or in fog.” Therefore, he
recommended directly to the CinCWA, “Our policy should be to invite the enemy to attack so that he can be destroyed.” This was to use merchant ships as bait, which Horton had rejected as “undesirable” in his Tactical Policy signal of 27 April. On 14 June, Horton responded (present writer’s emphases): “It is not agreed that it was desirable
at the time this convoy was run
to route convoys—particularly slow ones—so as to invite attack. If the changed situation which now prevails in the Atlantic were to be maintained, the routing of fast convoys when covered by support groups across the end of a patrol line so as to invite attack by a small number of U/Boats
deserves consideration.…
“
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Even at that date, in mid-June, Horton was guarded and hesitant in his expressions, but in retrospect it is clear that his long-established policy of Defender was tentatively yielding primacy to one of Hunter.

On 13 May, the Newfoundland
Daily News
published a front-page article under the headline: 10 nazi subs destroyed in convoy attack. The account, datelined London the day before and transmitted by Reuters, was based on an Admiralty communiqué that did not identify the convoy but did give a summary of anti-submarine attacks by escort ships, which were named, and by RCAF aircraft, though the number of U-boats definitely destroyed in the story did not match up to the number in the headline.
The Times
of London ran basically the same story on the same day, but was more discriminating in citing the U-boat casualties as four destroyed, four very probably destroyed, and two probably destroyed.
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Following these two accounts, however, there was little public attention and even less scholarly notice given to the Battle for ONS.5. Prime Minister Winston Churchill, who was in Washington, D.C., at the time of the communiqué, sent a congratulatory message to the escorts via the Admiralty on 9 May—my compliments to you on your fight against the u-boats—but eight years later, in 1951, when writing the fifth volume of his history,
The Second World War
, the volume that treated of the Atlantic war in this particular period, he did not think the battle noteworthy enough to mention.
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Similarly, the official historian of Royal Navy operations during the war, Captain Stephen W. Roskill, D.S.C., R.N., devoted a mere page and a half to the battle
in his three-volume history,
The War at Sea
, 1939–1945, published in 1956. To be fair, he allotted only twenty-one lines to the big battle of SC.122/HX.229 in the foregoing March.

Horton seems to have been the first to have grasped the decisive character of the ONS.5 triumph, suggesting that it would prove to be a “turning point” in the Atlantic struggle. Rodger Winn, in the OIC Tracking Room, wrote sometime within two and a half years of the battle: “This was probably the most decisive of all convoy engagements. It represented the extreme and, as it happens, the last example of coordinated pack attacks.”
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The Most Secret documents containing Winn’s appreciation were not released to the Public Record Office until 1975. In the meantime, Captain Roskill’s assessment of the place that this individual battle occupied in the war against Germany underwent a striking transformation. Where the most that he was willing to say in 1956 was that ONS.5’s “adventurous passage” had led to “grave losses” for the U-boats, three years later, in a review of Karl Dönitz’s
Memoirs
in
The Sunday Times,
he was emboldened to state: “[Dönitz] considers that the passage of convoy ONS.5 in April-May 1943 marked the turning point in the long struggle, and I fully agree with him.” Comparing Gretton and Sherwood to the likes of Hawke and Nelson, Roskill added this flourish: “The seven-day battle fought against thirty U-boats is marked only by latitude and longitude and has no name by which it will be remembered; but it was, in its own way, as decisive as Quiberon Bay or the Nile.”
⁵⁹
Perhaps, when viewed on the larger stage of World War II, it would not be unreasonable to say that the set-piece Battle for ONS.5 was the Midway of the Atlantic.

The pendulum of war, which had swung so dangerously to the German side in March and had reverted to center in April, now swung sharply to the Allies’ side. In reflecting on the long, bitter combat experienced by both belligerents during the passage of ONS.5, one’s attention is particularly drawn to the B7 flotilla that was the convoy’s original escort. In late April that force of seven warships, of which the majority were corvettes, set out to protect an argosy of forty-three light-ballasted ships whose best speed was seven and a half knots. Their passage would take them through bow-stopping gales and iceinfested
seas. Their base course would be anticipated by German intelligence, resulting in their being attacked and chased at their northernmost position. They would have to pass through what remained of the Air Gap, with scanty overhead protection. And then they would fall into the fatal embrace of the largest U-boat attack force ever assembled against a single convoy—a force comprising as many U-boats as, at the time, the convoy and escorts had ships, and five times the number of RN defenders. By any objective standard their condition was desperate. Little wonder that Captain McCoy, whose EG3 had joined in support, said on 5 May that “the convoy was threatened with annihilation.” And merchantmen did suffer grievous losses. But
B7
close escort ships alone exacted a heavy toll from their assailants, and supporting escorts, both surface and air, made additional U-boat kills. Every man who had been on board the
B7
vessels, starting with Gretton, who drew up the game plan, and Sherwood, who executed it, down to the lowest ratings in the boiler and engine rooms, deserved the highest credit. Against all odds, the
B7
ships and crews survived and prevailed. In the long Atlantic struggle against the U-boats, theirs truly was a sword-from-the-stone triumph. In looking through British naval/military annals for comparisons, one is tempted to recall Rorke’s Drift in 1879, where eighty men of the 24th Regiment of Foot defended the mission station against similarly overwhelming numbers. But Captain McCoy of EG3 will have the last word: “The skill, determination, and good drill displayed by all ships of B.7 Group during the time the Third Escort Group was supporting O.N.S.5 was beyond all praise.”
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I
T IS NOT KNOWN WHETHER
forty-seven-year-old American economist Stephen Raushenbush had ever seen a submarine or a bomber before he was suddenly posted to London in December 1942 to help develop a new battle plan for the Bay of Biscay. Military tactics were not something in which he had had any great interest since 1917–1919, when he and most of his graduating class at Amherst College went to
France with the American Expeditionary Force, he to serve as a volunteer ambulance driver. Though in that capacity he pursued his famous father’s compassionate ideals, he did not follow the Reverend Walter Raushenbush (1861–1918), a leading exponent of the Social Gospel, into the Baptist ministry. Instead, after the Armistice, he studied economics at the University of Rennes in France, worked in the oil industry in Mexico and Venezuela, researched coal and power issues in New York City, taught at Dartmouth College, and served for eight years as advisor on public utilities to the governor of Pennsylvania, while taking time out in 1934–1936 to be chief investigator for the Special U.S. Senate Committee that inquired into the munitions industry. In his spare time he wrote seven books, ranging in subject matter from
The Anthracite Question
(1923) to
The March of Fascism
(1939).

His last pre-World War II position, beginning in 1939, was with the U.S. Department of the Interior as chief of the Branch of Planning and Research in the Division of Power. He was described at that period of his life as a reserved but friendly person; he wore a mustache and smoked a pipe; though a registered Republican, he expressed political views that were liberal and progressive. Shortly after Pearl Harbor, he took a leave of absence from Interior to serve as a civilian economist and statistician in the office of the Chief of Naval Operations (CNO) in the Navy Department. From there, in late 1942, he was plucked by Captain Thorvald A. Solberg, U.S.N., Head of the Navy Technical Station, Office of the U.S. Naval Attaché (Alusna), London, to undertake air operations planning for the Bay of Biscay.
¹

In the U.K., Raushenbush quickly familiarized himself with the attack opportunities in the Bay as well as with Coastal Command’s disappointing success rate there. Since June 1942 Coastal had flown about 7,000 hours and lost aircraft at a rate of about sixteen for every U-boat sunk in the Bay. Since October only twenty-two air attacks had been mounted on the estimated 290 boats that had passed through the Bay.
²
The effort was out of all proportion to the meager results obtained. Raushenbush then set about studying the hardware. Near Glasgow on the Clyde he examined the Type VIIC U-570, captured in August 1941 and renamed H.M.S.
Graph
, and learned her operating characteristics,
paying special attention to the boat’s capacity for remaining submerged (36–41 hours) and the time required on the surface for fully charging her batteries (6.77–7.77 hours).

At various Coastal bases he studied the type of aircraft that were being flown on Bay patrols and took fascinated notice of new centimetric radar equipment that was just then becoming available for airborne use. At both Whitehall and Northwood he availed himself of the vast operations research data that had been accumulated by Professors Blackett and Williams and their scientific teams, whom Raushenbush found “tired and exhausted from too many seven day weeks.”
³
From Williams in particular, who had continued Bay Offensive studies at Coastal during the year following Blackett’s departure for other ASW challenges at the Admiralty, and who was later quoted by Blackett as saying that while his scholarly specialty was quantum theory, he “found the subtle intricacies of the U-boat war of comparable intellectual interest,” the American economist drew generous guidance and support.
⁴
In the end, not surprisingly, plans put forward to Churchill’s A.U. Committee by Raushenbush and Williams would bear a certain resemblance in conception, if not in details.

When he thought he understood the basic problems that the Bay presented, Raushenbush devoted himself to intense deskwork studies and statistical tables. His roommate at Alusna, Commander Oscar A. de Lima, U.S.N.R., remembered the economist’s “endless days and nights of complicated computations,” though the endless period was just over a month.
⁵
Raushenbush’s interests were most closely focused on the new availability of “Most Secret” 10-centimeter airborne radar, for which the Germans had no search receiver (G.S.R.). According to a report submitted on 22 December by radar pioneer Watson Watt, the Kriegsmarine would probably not figure out the wavelength, develop an answering G.S.R., and install it in the majority of their boats before “two or three months at the most” after first use of the Allied equipment.
⁶

“There was great promise in this situation,” Raushenbush wrote privately in 1948. “The danger in it was that the new weapon might (like tanks in 1916) be used in too small numbers, with too small effect, and that the Germans would consequently be given ample notice of the new
weapon before it could be used against them with telling effect, and would be ready for it.” He anguished, he wrote, over the possibility that a centimetric radar installation would first be used in an area such as the Mediterranean or the European mainland, where it might be captured and compromised.
⁷
As it happened, a few Io-centimeter sets were flown by Coastal aircraft out of Gibraltar in February before their use in the Bay. And Raushenbush’s worst-case scenario—though it is not known that he was aware of it at the time—unfolded on
2
February when an RAF Bomber Command Stirling bomber equipped with centimetric radar went down at night near Rotterdam. The radar set was Type
H2S,
in which the radar pulses were used in a “look-down” mode for picking out coastlines, lakes, waterways, and (less successfully) cities.

Coastal had forcefully opposed that use of
10
-centimeter radar prior to its use in the Bay precisely because capture of the equipment, which seemed likely, would ruin Coastal’s chances of obtaining surprise in the Biscay transit area. But Bomber Command spoke louder, claiming that for the success of the night-bombing campaign over Germany—always the overriding imperative in the Prime Minister’s mind—the bombers desperately needed
H2S
as a navigational aid. Churchill gave approval for the new radar’s use over enemy territory beginning in January, with, as Coastal feared, predictable results. Though the Stirling’s radar equipment was badly damaged, German technicians were able to reassemble the
Rotterdam Gerät
, as they called it, at the Telefunken laboratories in Berlin. By chance, the device was badly damaged a second time in an RAF bombing raid. Again, it was reconstructed, this time in a bombproof bunker. After flight-testing the magnetron valve equipment, the technicians realized that the Allies had achieved a major technological breakthrough, and, where the maritime war was concerned, had leapfrogged the Fu.MB (Metox). News of the disclosure was passed at once to BdU, where on
5
March the Dönitz/Godt war diary reported a confirming incident at sea and ruminated on the
Rotterdam Gerät.

The secret was out, and it appeared likely that the Germans would now neutralize the centimetric wavelength in the same way that Metox had neutralized the metric. But the Telefunken Company experienced problems in replicating parts of the Allied equipment, and administrative muddles further checked what was to have been a crash program to develop a new G.S.R., with the result, astonishingly, that an effective detector called
Naxos-U
was not shipped to the U-boats until October, far later than the two or three months predicted by Watson Watt, and long after the issue in the Atlantic had been decided.

Raushenbush began his calculations with a review of U-boat performance figures. The optimum (as against maximum) speed surfaced for charging batteries was 12 knots. The optimum speed for running submerged was 1.75 knots. The average battery capacity on entering the 200-mile-deep transit channel was 51 miles submerged, after which a U-boat had to surface for maximum recharge for a period of 6.77 to 7.77 hours, during which it would travel 81 to 93 miles. After another 51 miles submerged, it would have to surface for charging at least once again, briefly, until completing the 200 miles (assuming a direct course) in a total traverse time of 76.37 hours.

Thus, a U-boat in transit would be on the surface and vulnerable to air attack for at least one lengthy period. Any attempt to remain underwater beyond 41 hours would exhaust the air supply, although a boat could surface for 5 to 10 minutes to ventilate. A surfaced U-boat forced to dive by aircraft would later have to charge for approximately seven minutes to compensate for the 100 ampere hours used in one cycle of crash-diving and resurfacing. Since the average density of boats in the transit area at any given time was 15.8 boats, that number together would be exposed from 1,280 to 1,470 miles during their passage.
Raushenbush calculated that there would be a density of one surfaced boat per 3,800 square miles.

On the air side, Raushenbush called for an additional 160 long-range aircraft, all equipped with ASV Mark III and many with Leigh Lights, to make up a total force of 260 aircraft. Such a large, coordinated force, trained to capitalize on the Allied advantage of centimetric radar, could be expected to make 7.5 sorties per aircraft per month, to make 1.8 attacks on each of 150 U-boats entering the transit channel each month, to make a minimum of twenty-five kills per month, and to cause damage to a further thirty-four boats. Over the projected 120 operational days of this effort, 100 boats would be destroyed and 136 damaged, thus “paralyzing” the U-boat fleet and throwing it on the defensive. The damaged boats would play their role in the paralysis effect by jamming and overloading the Biscay repair bases.

There were two critical factors in the Raushenbush Plan: (1) the attack program must be put into effect
promptly
, before the enemy devised a centimetric search receiver; and (2) the attacking force must be
sufficiently large from the outset
; “no small driblets” of additional aircraft would make the plan work. On the second point he elaborated that a law of increasing returns could be developed to show that up to a certain point, a large but still less than adequate force would produce only minor results; but that once enlarged to and beyond a certain critical mass, the effectiveness of that force was in high progression. He concluded:

Raushenbush went on to suggest crew “mutiny” as a possibility, which was going somewhat over the top; the suggestion probably showed the degree to which his views were shaped by British associates, among whom the morale war seems to have been a preoccupation.
One suspects, knowing how U-boat crews put out to sea unflinchingly in 1945, when certain to near-certain destruction faced every boat, that infidelity to duty in the U-Bootwaffe was never a consideration.

The Raushenbush Plan was endorsed by Captain Solberg, and, upon his recommendation, by Admiral Harold R. Stark, U.S.N., Commander, United States Naval Forces in Europe, who had it printed up for presentation to the Prime Minister’s A.U. Committee on 24 March. In the meantime, it received strong support from the operations research team at the Admiralty, though those politically savvy people knew that the Plan would not fly unless it passed the inspection of Churchill’s personal science advisor, Professor Lindemann, now Lord Cherwell. Accordingly, Professors Blackett and Williams (the latter now also with the Admiralty) joined Raushenbush to form a special committee under the chairmanship of Sir Stafford Cripps, Minister of Aircraft Production and vice-chair of the A.U. Committee, for the purpose of bringing Cherwell into camp. In that endeavor they were not entirely unsuccessful.

Cherwell was at first dismissive of the Raushenbush Plan as “based upon somewhat speculative foundations,” calling it “unduly optimistic.” Without directly challenging any of the American’s numbers or calculations, he rejected the “largely theoretical” proposals in the Plan as diverging from prior practical experience in the Bay, where the dividends had been very few. Furthermore, he argued, the presumed advantage of 10-centimeter radar would be overcome “very easily” by a new German search receiver; and the probability that the enemy would sprinkle the Bay with radio decoys seemed to have been treated “rather lightly” by Raushenbush. It would be better, Cherwell said, to devote aircraft resources to the more fruitful duty of protecting menaced convoys. In fact, better still would be the allocation of Coastal Command aircraft to the bombing of German cities, which “must have more immediate effect on the course of the war in 1943.” All that said, however, Cherwell did allow that it could be an “interesting experiment” to give the Raushenbush advocates a free run to see how they fared.
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